I went to Catholic schools from kindergarten up until college. Part of the required curriculum every year was a class on religion. One day in my freshman year of high school, my "values and morals" class teacher made us watch a virulently anti-abortion propaganda film. The film was such a blatant and shameless piece of propaganda (e.g., it had a scene of evil abortionists literally cackling over a rich banquet in an opulent mansion) that so contradicted what I knew to be true of the world (e.g., doctors that performed abortions were called gynecologists and obstetricians and not "abortionists", they didn't live in mansions, but in the subdivision down the street, and they were just as inoffensively nice as the rest of our neighbors) that for the first time in my life I sat down and gave some serious thought to everything I'd ever learned in a religion class up until that point. If they were lying about Dr. James and the care he gave to his patients, what else were they lying about?
After that point I started thinking and reading more about religious doctrine and dogma (not just Roman Catholic, but all the other religions I'd learned about over the years, as well as my own religious tradition (Greek Orthodox). I read more religious and general history, as well as some philosophy (Euthyphro dilemma, etc.). I spent several years thinking about the problem of evil, and especially the problem of suffering, which still, in my mind, are the strongest philosophical arguments against god. What I was learning about animal and human development in biology class also contributed to the growing realization that there wasn't a god out there, at least not a god in the way Christianity or any of the other major world religions described him.
I got to college and majored in government (political science) and studied more political philosophy. Learned about Plato's "noble lie" and with amusement and annoyance I realized how many of the religious and political leaders in our society appeared to subscribe to the concept, all while preaching about democracy and the will of the majority.
And on a personal level, I realized I could be good without god (it didn't take me until college to realize this, btw :lol ). I could make rational decisions about how to treat other people and hew to a moral code without basing my thoughts and actions in the concept of a invisible divine Watcher. I could experience awe at a parent's love for a child or in a beautiful landscape without having to rely on the idea that god made either. That was and is an enormously powerful realization for me. It felt like I had finally grown up. To go back to Plato again, I felt like I'd come out of the cave.
At this point, I don't hate religion. I actually find it pretty interesting as a cultural and sociological phenomenon. I do know that I've outgrown any emotional need I have for it. (I still go to church on occasion since I like hearing Greek and watching the liturgy - it's like a little piece of Byzantium has been transported right to my neighborhood. :lol) I've accepted the fact that one day I will die and that will be the end of my consciousness. That makes me sad since I love being alive, and the world, even with all its misery, is an amazing place, but it's still better (for me at least), than believing in the lie that I'll meet all my loved ones again after death. All I can do is love my friends and family as much as I can right now, since this life is all I will ever get.